Virtual Contest Reunion - New Prizes....

[EMRR]

Originally posted by RocketmanTM
My rocket looks oh so much more spiffy with it's decals on!

RockSIM 7 to RockSIM 8 bug... I had to manually fix it.

Look how big your rocket is compared to ALL other entries...

Regards,
Nick

 

[EMRR]

The files will be available soon and then you folks should look at CD's on the various rockets. Large difference:

Levison at 913 ft/s (M900 max velocity) = 2.84
Mullin at 955 ft/s (M900 max velocity) = 1.02
Cox at 1655 ft/s (M900 max velocity) = 0.816
Davis at 1158 ft/s (M900 max velocity) = 0.843

Food for thought...

Okay, now I've moved on.

Nick

 

[n3tjm]

Am I really second standing? Looks to me that someone else is looking at the results of the data.

 

[BobCox]

The drag coefficients vary over a range of about 3:1. That could easily explain the variation for the C11 and E6 flights.

-------------

Event 4: Takeoff Times.
I put most of my effort into getting the fastest takeoff time. I managed to barely have the best time, even though my weight is only about half that of the next lightest. It turns out that the motor accounts for about 85% of the takeoff weight, so shaving weight off the rocket makes very minor improvements in takeoff speed, but has huge impacts in Event #1 scoring. I feel dumb dumb dumb for not seeing that sooner.

As Chan Steven pointed out, a lot of people used F72 engines to get rapid takeoffs. As the attached plot shows, that was a good choice. The blue dots are F72, orange dots are other engines. Note how the F72 turns in the fastest takeoff times for their weight.

Rocketeer	Weight	Engine	Time
Bob Cox	         0.4329	F72	0.050
Chris Coffin	 0.9054	F72	0.054
Dave Austerberry 1.5352	F72	0.059
Brandon Harrison 1.7088	F72	0.061
Jeff Henry	 0.7889	F39	0.062
Bruce Levison	 1.855	F72	0.063
Clive Davis	 0.8861	E30	0.064
Bill Cooke	 1.323	E30	0.065
Andy Peart	 1.8542	G55	0.066
Frank Ross	 0.983	E28	0.067
Chan Stevens	 2.6861	F72	0.068
Jeff Lane	 2.9117	F72	0.069
Morgan Lee	 3.4793	F72	0.071
Steve Naquin	 3.0277	G55	0.072
Claude Paquin	 1.5868	E30	0.072
Peter Stanley	 0.5634	F32	0.072
Jim Myers	 5.0549	F72	0.075
Douglas Gardei	 2.7904	F39	0.075
Eric Maglio	 5.5041	F72	0.077
Layne Pemberton	 5.4767	F72	0.077
Geoffrey Kerbel	 3.698	F39	0.082
Todd Mullin	 5.2273	G55	0.089
Phil Handley	 3.7456	G37	0.090
Nathan Schoenkin 3.1799	F32	0.092
Mark Thompson	 6.4093	F21	0.108
Michael Mangieri 1.0698	D12	0.186
Andrew Dobos	 3.966	E9	0.266

 

[BobCox]

Originally posted by n3tjm
Am I really second standing? Looks to me that someone else is looking at the results of the data.

Yeah, it looks to me like you are in second after Event #3, with a tiny 0.2 point lead over Steve Naquin in 3rd.

The top 10 scores are quite close together. Just a few points difference in the drag race could have a big effect on the final standings.

 

[chanstevens]

Originally posted by BobCox
The drag coefficients vary over a range of about 3:1. That could easily explain the variation for the C11 and E6 flights.

-------------

Event 4: Takeoff Times.
I put most of my effort into getting the fastest takeoff time. I managed to barely have the best time, even though my weight is only about half that of the next lightest. It turns out that the motor accounts for about 85% of the takeoff weight, so shaving weight off the rocket makes very minor improvements in takeoff speed, but has huge impacts in Event #1 scoring. I feel dumb dumb dumb for not seeing that sooner.

Great analysis Bob!

That does sort of reinforce what I'd suspected, but now can see quantitatively. My bird, for example, weighs about 6 times what yours does. You'd have to gain more than 6x my altitude in event #1 to equal my score the way the scoring worked. There's no way your design was going to be low enough drag to overcome that multiplier difference. Fast forward to drag race--as you pointed out, the motor weight is the main portion of the total weight. Peak performance is thrust curve spike and low drag. My heavy design didn't fare as well as I'd hoped, but still left the rod at a semi-repsectable 0.068. I hoped to get far enough out in front to hang onto a lead at the end. I just didn't expect so many others would catch on to the hot motor strategy, and am blown away by how well the field has advanced in low drag (and tube fin) designs. I have no idea where my next "edge" might come from, and am glad I'm likely hosting the next contest rather than competing in it.

 

[EMRR]

Originally posted by BobCox

Jeff Henry 0.7889 F39 0.062
Clive Davis 0.8861 E30 0.064
Bill Cooke 1.323 E30 0.065
Frank Ross 0.983 E28 0.067
[/CODE]

These really surprised me. I went back and checked settings.

Nick

 

[teflonrocketry1]

Originally posted by BobCox
Yeah, it looks to me like you are in second after Event #3, with a tiny 0.2 point lead over Steve Naquin in 3rd.

The top 10 scores are quite close together. Just a few points difference in the drag race could have a big effect on the final standings.

Bob,

If you think you have a reason to be embarrassed by your design, take a look at my entry the Twin-Boomer. I think I am solidly in last place. This design wasn't even worth the time I spent building it, what a complete waste. I am sure it will make a great blast deflector. I didn't catch the flaw in the RockSim software until after I submitted the design. Design any ring tail fin rocket and that fin makes up more than 90% of the Cd value. No way this can be right.

Bruce S. Levison, NAR #69055

 

[EMRR]

Everyone is beating themselves up too much.

Remember this the "full of luck" contest, modeled after the very first one. When more choice and less luck is involved that really shows off the skills of you folks.

I'm impressed with the newbies that are participating.

2 phase of the drag race is up!

Tomorrow all will know what the results are!

Nick

 

[PunkRocketScience]

I'm not really beating myself up on contest #1, just kinda suprised. Ah well... I had designed my rocket more with the "beauty contest" in mind...only to re-read the rules afterward and find out that there wasn't one...

Not that I'm volunteering to run another contest quite yet, but here's a possible suggestion for a future contest. I always seem to have at least two different designs that I have to choose between to enter. How about a contest that allows more than one entry? Of course there would have to be a limitation on how many prizes Bob and Chan could take home....

One other thought, Nick. Is the contest that Bill Krosney proposed going to ever go? I WOULD volunteer to run one along those lines....

 

[EMRR]

Well, the Steven's Open is next.

Then the Paquin Open.

Then we could have a Krosney Memorial hosted by Mullin if we desire.

Thanks for offering.

Nick

 

[ccoffin]

So what was the wind speed in event #4?

 

[EMRR]

Originally posted by ccoffin
So what was the wind speed in event #4?

Sorry, I should have posted that: Constant 3 MPH, no Thermals

Nick

 

[PunkRocketScience]

Oooo....Open mouth...insert foot (or keyboard...) I had not heard the reason that Mr. Krosney's contest had not gone live...

I'd be pleased to run The Krosney Memorial. Sign me up after Stevens and Paquin!

 

[EMRR]

Originally posted by RocketmanTM
Oooo....Open mouth...insert foot (or keyboard...) I had not heard the reason that Mr. Krosney's contest had not gone live...

I'd be pleased to run The Krosney Memorial. Sign me up after Stevens and Paquin!

No, no... sorry... my bad. I'm not saying that he actually passed-away. I'm saying there has been no contact in months, on months!

I will drop the memorial statement from this point forward. Keyboard is in my mouth.

Nick

 

[BobCox]

Congratulations to Chan for a great win using smart strategy.

Dave Austerberry is now officially on my "hit list", with his third top-3 finish in four contests.

And thanks to Nick for running this contest again. This one had the highest turnout yet, and I know how much work it is to go through that many entries.

----------------------------
It looks my drag-race strategy worked pretty well: Take off fast, then do a free-fall kamikaze dive back to the launch pad. Too bad (for me) that I focused so much on this event and completely blew Event #1 (I expected to do poorly in #3, but I was blind-sided by my dismal performance in Event #1).

Like Jeff Henry, I expected to do much better than I did, in 14th place. That is by far my worst finish.

I only spent about 2-4 hours on this contest, compared to 20-40 hours on previous contests. You can bet that I will work harder on the next one.

 

[n3tjm]

Suggestion: We need comments for each of the events, especially for the top players. I find the data confusing, and with the comment about how my F39 stacked against the larger 24mm's, It would be easier to compair if the user motor choice was in results table ^^

Anyone care to guess why I chose the F39 versus the larger 24mm motors?

 

[BobCox]

Originally posted by n3tjm
Suggestion: We need comments for each of the events, especially for the top players. I find the data confusing, and with the comment about how my F39 stacked against the larger 24mm's, It would be easier to compair if the user motor choice was in results table

Like this?
Drag Race Results, Sorted by Point Total

Entry#	Weight	Engine	Angle	Clear	Rank	Land	Rank	Range	Rank	Total	POINTS	Rocketeer
24	1.5352	F72-10	-21.4	0.059	25	300	20	629	14	59	27	Dave Austerberry
21	0.7889	F39-9	-28	0.062	23	272	17	467	17	57	26	Jeff Henry
15	0.4329	F72-N	-1	0.05	27	62	1	43	27	55	25	Bob Cox
10	1.7088	F72-10	-26.5	0.061	24	281	19	1090	7	50	24	Brandon Harrison
5	1.855	F72-5	-30	0.063	22	139	6	348	20	48	22	Bruce Levison
17	0.9054	F72-10	-13.562	0.054	26	178	11	866	11	48	22	Chris Coffin
6	1.323	E30-7	5	0.065	20	116	4	149	23	47	18	Bill Cooke
7	3.7456	G37-6	-10	0.09	5	324	21	342	21	47	18	Phil Handley
14	3.4793	F72-10	-25	0.071	15	227	16	515	16	47	18	Morgan Lee
25	1.8542	G55-15	-3	0.066	19	1696	26	6699	2	47	18	Andy Peart
2	3.0277	G55-5	-2	0.072	12	159	8	96	26	46	15	Steve Naquin
11	3.698	F39-9	-15	0.082	7	202	14	117	25	46	15	Geoffrey Kerbel
23	0.8861	E30-7	-30	0.064	21	191	12	742	13	46	15	Clive Davis
1	2.6861	F72-10	-30	0.068	17	412	22	1727	6	45	14	Chan Stevens
20	2.7904	F39-9	-5	0.075	10	177	10	256	22	42	12	Douglas Gardei
22	2.9117	F72-15	-30	0.069	16	464	23	4069	3	42	12	Jeff Lane
3	0.983	E28-5	-17	0.067	18	122	5	414	18	41	11	Frank Ross
12	1.5868	E30-7	-30	0.072	12	208	15	829	12	39	9	Claude Paquin
19	5.0549	F72-10	0	0.075	10	814	25	3513	4	39	9	Jim Myers
4	5.2273	G55-10	-30	0.089	6	2137	27	6932	1	34	7	Todd Mullin
27	0.5634	F32-10	1	0.072	12	145	7	604	15	34	7	Peter Stanley
16	3.1799	F32-12	-2	0.092	4	277	18	915	10	32	6	Nathan Schoenkin
13	1.0698	D12-7	0	0.186	2	587	24	2492	5	31	5	Michael Mangieri
9	5.4767	F72-10	3.126	0.077	8	193	13	961	9	30	4	Layne Pemberton
18	6.4093	F21-8	-7	0.108	3	93	2	122	24	29	3	Mark Thompson
8	5.5041	F72-10	7	0.077	8	166	9	1048	8	25	2	Eric Maglio
26	3.966	E9-6	0	0.266	1	109	3	367	19	23	1	Andrew Dobos

Anyone care to guess why I chose the F39 versus the larger 24mm motors?

I'll take a wild stab... Longer lower thrust will make you weathercock more, offsetting the parachute drift. The net result is that your landing position will be less sensitive to differences in wind. How's that for a guess?

 

[EMRR]

Hold the press release, we have a contested result on two entries:

Jeff Lane's use of material thicknesses of .001 tubing. I missed that. The rules in question are:

+ Materials must be standard weights that are in the rocksim database
+ Materials must be standard thicknesses that are in the rocksim database

I will allow until Saturday Midnight for open discussion (files will all be up soon).

After that I will make a final call and close on prize selections.

Thanks,
Nick

 

[EMRR]

Originally posted by n3tjm
Suggestion: We need comments for each of the events, especially for the top players. I find the data confusing, and with the comment about how my F39 stacked against the larger 24mm's, It would be easier to compair if the user motor choice was in results table ^^

Anyone care to guess why I chose the F39 versus the larger 24mm motors?

Added the Motor to the table. It is all a matter of time...

RockSIM and ZIPs posted including an all-in-one ZIP Pack.

Nick

 

[BobCox]

Originally posted by EMRR
Hold the press release, we have a contested result on two entries:

Jeff Lane's use of material thicknesses of .001 tubing. I missed that. The rules in question are:

+ Materials must be standard weights that are in the rocksim database
+ Materials must be standard thicknesses that are in the rocksim database

I will allow until Saturday Midnight for open discussion (files will all be up soon).

After that I will make a final call and close on prize selections.

Thanks,
Nick

That's a tough call. If it had been pointed out sooner, Jeff could have easily changed it. Disqualifying him after the contest is over doesn't seem fair to Jeff, but on the other hand it's not fair to the other contestants who followed all the rules.

I looked at Jeff's design more closely. Jeff didn't benefit very much from the lightweight custom tubing. If you look at his design, 93% of its weight comes from a solid brass transition. Reverting to official tubing would have only added about 0.2 oz, which he could have easily taken out of the brass transition.

Based on the results for each of the events, I don't think an extra 0.2 oz would have had much effect on the final standings.

 

[SwingWing]

Originally posted by EMRR
Hold the press release, we have a contested result on two entries:

Jeff Lane's use of material thicknesses of .001 tubing. I missed that. snip.....

Thanks,
Nick

That's one, what was the second???

I agree with Bob that it was likey an honest mistake. Is there an easy way to check and see if it tipped the scales in his favor much??

 

[EMRR]

Sorry - I checked the second and found it to be okay. Missing second set of fins on Coffin, but they are there.

Nick

 

[BobCox]

Originally posted by Henry8minus1
When designing rockets for the Virtual Contests how realistic do they have to be? Or better stated do you have to design a rocket that could actually be built in the real world, or just one that works in RockSim?

I do realize that because this is virtual that we can get away with things that wouldn't really work, like a 24mm M motor.

My approach in both contests in which I have participated was to try to design a rocket that would actually work in the real world.

I attribute my early success in the the Virtual Rocket Contests to my INexperience in the real world of rocketry. A real Level I rocket would use heavy tubing, thick coupler, playwood or fiberglass fins, strong engine mounts. In virtual world, Estes tubing and thin balsa fins are sufficient, motor tubes don't need centering rings or engine blocks, transitions and nose cones don't need shoulders, etc. In virtual contests I usually try to make my designs somewhat realistic.

Because of this I used shoulders on my tranistions because I don't know how to build a rocket without them (EDIT: If you know a good way to do this I would like to learn).

Attach two centering ring to the smaller tube, one flush with the bottom end, the other 1 to 2 calibers up from the end. Insert into the larger tube, leaving the upper ring flush with the end of the large tube. A paper shroud or hollow balsa transition can then be wrapped around the assembly.

I noticed that many designs don't have shoulders, and a couple of designs used solid balsa tranistions (without shoulders) that somehow let ejection gasses pass through them.

That is probably a simple oversight, and makes little difference on balsa blocks.

Also when you are calculating the margin of stability do you use the nosecone base diameter or the max frontal diameter?

I usually use the default (nosecone diameter), but if the nose cone is far smaller than most of the body (like the escape tower on a Saturn V), then I use the "average" body diameter.

 

[teflonrocketry1]

I designed a rocket for this contest and actually built it! It flies much better than the vitual design because of a flaw in the RockSim version 8 software. I only noticed this after I submitted my design. If I had used my approximation techniques instead of the RockSim version 8 software's tube and ring tail fin simulations, I would have placed much better in the contest events.

Nick,

Rules are rules, and the decision of the judges is final. It was up to the contestants to follow the rules and the judge to check that the rules were followed. If you allowed the flaw initially why are you changing your mind now? If this oversight cheated someone out of a prize then find a way to make it up to them.

Bruce S. Levison, NAR #69055

 

[EMRR]

Looks like I have a left over prize from the NASROC contest, so we will apply that to this contest.

I have not heard from all the prize winners. It is currently stuck at Andy Peart. He has notified me, but has not picked a prize.

Jeff Lane's rocket and position stands.

Moving on.

Nick

 

[ccoffin]

Where is the prize picking at now?

You got my reply right?

 

[EMRR]

Stuck on Peart. He has until midnight tonight and then I move on.

 

[PunkRocketScience]

I'll call him and let him know... I sent him an e-mail this morning...

 

[PunkRocketScience]

Andy is having e-mail problems for some reason. I have forwarded his choices to Nick. He apologizes about the delay.

So, Chan.... are you going to give us any hints as to what your contest will be?